package com.sjgtw.cloud.gateway.filter;

import java.util.Collections;
import java.util.List;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.OrderedGatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.http.HttpMethod;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

/**
 * <p>Title: CacheRequestFilter</p>
 * <p>Description: </p>
 * @author Admin
 * @date 2021-4-9
 */
@Component
public class CacheRequestFilter extends AbstractGatewayFilterFactory<CacheRequestFilter.Config> {
	public CacheRequestFilter() {
		super(Config.class);
	}

	@Override
	public String name() {
		return "CacheRequestFilter";
	}

	@Override
	public GatewayFilter apply(Config config) {
		CacheRequestGatewayFilter cacheRequestGatewayFilter = new CacheRequestGatewayFilter();
		Integer order = config.getOrder();
		if (order == null) {
			return cacheRequestGatewayFilter;
		}
		return new OrderedGatewayFilter(cacheRequestGatewayFilter, order);
	}

	public static class CacheRequestGatewayFilter implements GatewayFilter {
		@Override
		public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
			HttpMethod method = exchange.getRequest().getMethod();
			if (method == null || method.matches("GET") || method.matches("DELETE")) {
				return chain.filter(exchange);
			}
			return DataBufferUtils.join(exchange.getRequest().getBody()).map(dataBuffer -> {
				byte[] bytes = new byte[dataBuffer.readableByteCount()];
				dataBuffer.read(bytes);
				DataBufferUtils.release(dataBuffer);
				return bytes;
			}).defaultIfEmpty(new byte[0]).flatMap(bytes -> {
				DataBufferFactory dataBufferFactory = exchange.getResponse().bufferFactory();
				ServerHttpRequestDecorator decorator = new ServerHttpRequestDecorator(exchange.getRequest()) {
					@Override
					public Flux<DataBuffer> getBody() {
						if (bytes.length > 0) {
							return Flux.just(dataBufferFactory.wrap(bytes));
						}
						return Flux.empty();
					}
				};
				return chain.filter(exchange.mutate().request(decorator).build());
			});
		}
	}

	@Override
	public List<String> shortcutFieldOrder() {
		return Collections.singletonList("order");
	}

	static class Config {
		private Integer order;

		public Integer getOrder() {
			return order;
		}

		public void setOrder(Integer order) {
			this.order = order;
		}
	}
}